The friend scale goes like this:
Lv1 Mate = Person you hang out with from time to time
Lv2 Friend = Person you hang out with on a regular basis
Lv3 Good Friend = Person you hang out with and whom you take on camping trips and festivals
Lv4 Best Friend = Person you'd lend a 1000$ in cash without setting up an I.O.U.
Lv5 Very Best Friend = Person you'd take along to a bank robbery and invite to a threesome with...
Lv6 Girlfriend/Boyfriend = Figures.
Now the top level consists usually of one person, unless you got some sort of harem. The 2 levels below usually consist of very, very few people and normally people who you can stay in touch with after you graduated from school (facebook doesn't count). Levels 2 & 3 normally last only a few years, university days or such. Level 1 lasts a year at best.
On levels one to three you can usually just shit on them. Levels four to six take time to get to and they take care and trust, but when you're there it's the best thing that can happen.
Coincidentally, there is but one persone whom I truly consider a "best friend", I'd probably even would invite him to a bank robbery but the threesome is out of question here.
